Rationale: The current standard of respiratory monitoring for patients during deep sedation is continuous pulse oximetry with visual assessment of the patient. Clinical research has demonstrated that depressed respiratory activity is a principal risk factor for hypoxemia during sedation. Capnography may provide early detection of alveolar hypoventilation before hypoxemia has occurred in nonintubated patients and thereby improve patient safety during sedation.

Objective: At the Centre for Contraception, Sexuality and Abortion Leiden, abortion procedures are performed under deep sedation using propofol. Patient's monitoring is performed by nurses qualified in patient sedation management, using pulse oximetry and their clinical judgement. The aim of this study is to examine the effectiveness of capnography in early detection of alveolar hypoventilation during deep sedation in comparison to standard monitoring with pulse oximetry in abortion procedures.

Study design: This protocol describes a prospective, open, randomized controlled trial with two study arms. All patients receive standard care of monitoring performed by the medical staff. The study investigates whether capnography prevents patients from having respiratory events during deep sedation in abortion procedures by early detection and therapy. Patients randomized to the standard care group receive standard of respiratory monitoring using pulse oximetry. In the capnography arm, respiratory monitoring is performed with pulse oximetry and capnography.

Study population: The study population comprises female patients (≥ 18 years) undergoing abortion procedures during first or second trimester pregnancies. Abortion procedures are performed until 22 weeks of gestational age.

Capnography: In addition application of capnography during deep sedation with propofol is performed. Before the trial starts, all nurses qualified in patient sedation management and abortion doctors will be trained in assessment of capnography. In the capnography arm, patients' breathing is additionally monitored with capnography. If alveolar hypoventilation is detected medical staff will intervene by arousing the patient, performing chin lift, repositioning the head, provision of oxygen, or abandon from giving additional propofol. These interventions represent the standard of care currently used by the clinical staff to respond to hypoventilation and hypoxemia.

Main study parameters/endpoints: The primary outcome is the occurrence of oxygen saturations to ≤90% in the population, as measured by continuous pulse oximetry. Secondary study outcomes include occurrence of oxygen saturations < 80%, dose of administered propofol, arousal or movement of the patient during the procedure, airway interventions, early termination of the procedure due to respiratory problems, episodes of bradycardia, and administration of atropine.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The risks related to the conduct of this study are negligible and the burden minimal. Patients in both groups receive the current standard of care. Patients randomized in the capnography group could get benefit from the addition of capnography to the monitoring by early detection of alveolar hypoventilation. Capnography is a noninvasive measurement by means of a cannula under the nose, which before the sedation may tickle, but during sedation no inconvenience is expected.

Proportion of patients having saturations (SpO2 below 90%) in the two arms [ Time Frame: Desaturations during the sedation procedure, within 1 hour after administering the first propofol dose ] [ Designated as safety issue: Yes ]

proportion of patients necessitating airway interventions [ Time Frame: Airway interventions during the sedation procedure within 1 hour after the first propofol dose ] [ Designated as safety issue: No ]

Secondary study outcomes include airway interventions (repositioning the head, chinlift, supplemental oxygen, bag-mask ventilation), problems during the abortion procedure (e.g. arousal or movement of the patient), early termination of the procedure due to respiratory problems, episodes of bradycardia, administration of atropine.

Proportion of patients having deep desaturations (SpO2 below 80%) in the two study arms [ Time Frame: Desaturations during the sedation procedure, within 1 hour after the first propofol dose ] [ Designated as safety issue: Yes ]

Patients randomized to the standard care group receive standard of care using pulse oximetry

Experimental: Capnography

In the intervention group capnography is measured using a cannula under the nose connected to the capnograph. The capnographic device displays respiratory rate, end-tidal carbon dioxide (ETCO2) levels, and continuous waveforms.

Device: Capnography

In the capnography arm, respiratory monitoring is performed with pulse oximetry and capnography. If the capnogram indicates sub-optimal ventilation and/or apnea, denoted as a flat line on the capnometer for ≥ 15 seconds, a respiratory rate ≤ 6, or a end-tidal CO2 > 50 mmHg, medical staff will intervene by arousing the patient, performing chinlift or jawthrust, abandon from giving additional propofol, or provision of oxygen. The nurse qualified in sedation management will assess capnography him/ herself.

Patients were considered for enrolment if they fulfil all of the following inclusion criteria: age 18 years or older, abortion procedures performed until 22 weeks of gestational age, American Society of Anaesthesiologists (ASA) classes I to II, and ability (mental competence) to give informed consent.

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Please refer to this study by its ClinicalTrials.gov identifier: NCT01220765